Left-right (LR) asymmetry is a fundamental feature of internal anatomy, yet the emergence of morphological asymmetry remains one of the least understood phases of organogenesis. Asymmetric rotation of the intestine is directed by forces outside of the gut, but the morphogenetic events that generate anatomical asymmetry in other regions of the digestive tract remain unknown. Here we show that the mechanisms that drive the curvature of the stomach are intrinsic to the gut tube itself. The left wall of the primitive stomach expands more than the right wall, as the left epithelium becomes more polarized and undergoes radial rearrangement. These asymmetries exist across species, and are dependent on LR patterning genes, including FoxJ1, Nodal and Pitx2. Our findings have implications for how LR patterning manifests distinct types of morphological asymmetries in different contexts.
- Received August 15, 2016.
- Accepted February 21, 2017.